Telocytes in human isolated atrial amyloidosis: ultrastructural remodelling

Abstract

The human heart can be frequently affected by an organ-limited amyloidosis called isolated atrial amyloidosis (IAA). IAA is a frequent histopathological finding in patients with long-standing atrial fibrillation (AF). The aim of this paper was to investigate the ultrastructure of cardiomyocytes and telocytes in patients with AF and IAA. Human atrial biopsies were obtained from 37 patients undergoing cardiac surgery, 23 having AF (62%). Small fragments were harvested from the left and right atrial appendages and from the atrial sleeves of pulmonary veins and processed for electron microscopy (EM). Additional fragments were paraffin embedded for Congo-red staining. The EM examination certified that 17 patients had IAA and 82% of them had AF. EM showed that amyloid deposits, composed of characteristic 10-nm-thick filaments were strictly extra-cellular. Although, under light microscope some amyloid deposits seemed to be located within the cardiomyocyte cytoplasm, EM showed that these deposits are actually located in interstitial recesses. Moreover, EM revealed that telopodes, the long and slender processes of telocytes, usually surround the amyloid deposits limiting their spreading into the interstitium. Our results come to endorse the presumptive association of AF and IAA, and show the exclusive, extracellular localization of amyloid fibrils. The particular connection of telopodes with amyloid deposits suggests their involvement in isolated atrial amyloidosis and AF pathogenesis.

Effect of Melatonin on Telocytes in the Seminal Vesicle of the Soay Ram: An Immunohistochemical, Ultrastructural and Morphometrical Study

“…These heterocellular junctions may have a role in the regulation of the surrounding environment. Increasing evidence indicates that TCs might be implicated in tissue homeostasis and development , as well as in the pathogenesis of some disorders [Mandache et al, 2010]. The present study supports the theory that TCs have the capacity to either receive or generate molecular signals between them and the connected cells, which can influence the surrounding myocytes by paracrine mechanisms Cretoiu et al, 2011].…”

The Possible Protective Role of Melatonin on Doxorubicin Induced Cardiomyopathy of Adult Male Albino Rats

“…Telocytes are a distinct type of stromal cells described in the cardiac interstitium and termed 'telocytes' because of their long, slender processes (telopodes Tp) embracing the myocardial cells. The identification of these cells was based on ultrastructural criteria [44,45] .…”

MicroRNA-140 is elevated and mitofusin-1 is downregulated in the right ventricle of the Sugen5416/hypoxia/normoxia model of pulmonary arterial hypertension.

“…Alternatively, c-kit ϩ cells in the mammalian adult heart are endothelial cells (61), telocytes (3), or mast cells (75). Telocytes are involved in regeneration and/or repair of an organ and has been implicated in atrial remodeling (40) and mast cells in cardiac inflammation and myocardial remodeling (21,34). Thus the accumulation of c-kit ϩ cells was likely a consequence of the RV hypertrophy in PAH rats, but a contribution to the progressive deterioration of heart function and finally failure cannot be ruled out.…”